Sex Ethics Question: “Is dating a coworker OK?”

“You should never date up or down,” advises Nan DeMars, a workplace ethicist in Minneapolis. “You could lose your job and face legal ramifications.” If you’re equals, it’s OK as long as you’re professional (don’t get hands-y at the copier). But proceed with caution: If the relationship goes south, the fallout could be epic.

Sex Ethics Question: “Do I have to tell my husband I had lunch with my ex?”

We know it’s easier not to, but yes. “My rule is, don’t do anything you can’t tell him about,” says Mira Kirshenbaum, author of I Love You but I Don’t Trust You. “These things have a way of coming out, and even if what you did was innocent, the hiding will make it seem anything but.”

Sex Ethics Question: “If a guy goes down on me, do I need to reciprocate?”

“A blow job is never an obligation—only return the favor if you want to,” says Christi, 34, of Knoxville, Tennessee. “If he pushes your head down there, that’s just rude!” Logan Levkoff, Ph.D., a New York City sex educator, concurs: “Sex should never be tit for tat, though generally things should even out.”

“In a word, no—at least not without his explicit permission,” says Karen Stohr, Ph.D., a senior research scholar at the Kennedy Institute of Ethics in Washington, D.C., and author of On Manners. “It doesn’t matter whether we’re talking about texts, instant messages, emails, or personal letters, you owe it to the guy to respect his privacy.” Even when you sense he’s been dishonest and deserves a little CSI, think twice before you stoop to his alleged low. “If you have a reason to be suspicious,” Stohr says, “ask him about it straight-out.” Still want to snoop? “Know going in that he may find out and you’ll have to deal with his mistrust of you,” cautions Kirshenbaum.

Sex Ethics Question: “Do I have to be cool with his porn? It’s skanky.”

Strap-on orgies? Kinky army nurses? It’s amazing what some guys find wank-worthy. His fantasy world is probably just an escape, says Levkoff, but if the nature of the images bothers you, say so: “Ask him why he wants to watch porn, but also ask yourself why you’re insecure about it.” Do you worry that you’re not enough for him? That he’s thinking about being unfaithful? Talk it out.

Sex Ethics Question: “Can I fudge my online-dating profile?”

“People lie about their height, weight, and age in epidemic proportions,” says dating coach Evan Marc Katz, author of Why He Disappeared. “You’ll never see a 5’6” man online, for example; they’re always 5’9”. But I don’t condone it.” Given the way many dating sites are set up, however, Katz says it’s not terrible to shave your age from, say, 30 to 29 so your profile shows up in an “under 30” search. He just urges you to tell the truth in your longer profile. Adds Janelle, 32, of Atlanta, “If you fudge your info, you’re not just wasting other people’s time; you’re wasting yours.” When she met her husband online, he knew from the beginning that she was into cheesy eighties music, sarcasm, and sushi—and was an agnostic. “We got to skip that awkward ‘So, uh, do you go to church?’ conversation,” she says. “If you want a serious partner, you should be as honest as possible.” And especially when it comes to your picture, don’t mess around. “Using an old photo is misrepresenting yourself,” Katz says.

Sex Ethics Question: “Should I tell my sex partner that I have HPV?”

Obviously yes if you have genital warts, but what about the kind of HPV that just shows up on an abnormal Pap? Still yes, doctors say. You owe it to your fellow women! “The first time you’re having sex with someone, you’re not thinking about his next partner,” points out Katharine O’Connell White, M.D., an assistant professor of obstetrics and gynecology at the Tufts University School of Medicine in Boston. “But he can pass it on to her, and this is the type of HPV that causes cervical cancer.” And don’t be embarrassed: With 80 percent of adults estimated to get HPV in their lives, “it really is the new normal,” says Dr. White. Have a low-key chat—before any clothes come off—and always travel with a condom.

Sex Ethics Question: “Is it right to sleep with a guy who’s into me—but whom I’m not into?”

This one gets a yes(ish). “Women are certainly entitled to have sex for the sake of having sex,” says Levkoff. “But you need to be thoughtful.” Just make it clear up front that you want to only be friends with benefits. Here’s how, says Amy Levine, a New York City-based sex coach: “During a casual conversation, tell him you’re not looking for a relationship right now; you’re all about having a good time and living in the moment.” He should pick up on the encoded “You’re not going to be my boyfriend, OK?” To be sure he does, continues Levine, “look him in the eye and say, ‘Are you cool with that?’” If he clearly gets it, game on. If he looks crushed, run, warns a 35-year-old reader from Huntington, New York. “I once had a fling turn into a Stage Five Clinger—sending flowers, showing up at my office. The only way to get rid of him was to be mean, which I hated. I can still see his face when I told him he wasn’t my type and never would be.”

Sex Ethics Question: “What are the rules for setting up my friends?

Tread lightly here, says Stohr, who suggests reading Jane Austen’s Emma for some old-timey matchmaking mishaps (in a pinch, rent the Gwyneth movie version). Once you’ve helped your friends connect, your job is over. “Don’t share gossip, take sides, or run interference,” Stohr says. “Exerting too much influence is disrespectful and might damage your friendships.” Lucy, 33, of New York City, who has set up several friends, never breaks this rule: “I only share nice details about the other,” she says. “They can find out the rest from there.”